The data detailed above was provided courtesy of the Berkeley Enthusiasts Club.

The claimed peak power of the Excelsior engine was 18bhp @5,000rpm. Assuming that the car was geared for maximum achievable speed on the flat and at peak power revs, the top speed figure would be around 59mph.

The dotted lines indicate gear changes at peak power engine revs when changing up through the box - not a recommended driving practice! Also shown are reference speeds re. over-revving the engine (which is of relevance as ring flutter occurs at around 6,000rpm).